Which external hard drive for photography/video editing

Hello!!
I have an iMac, 2.4GHz, Leopard OSX...and am in the market for an external HD. I am a freelance photographer and will hopefully be doing video editing in the near future with Final Cut. I have a ton of photos to save, as well as video on DV.
Any help is greatly appreciated...I was looking into the Lacie, firewire compatable 500GB. Would 1TB be better for the long run?

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